In order to determine a rotational acceleration and/or a linear acceleration acting on a movable body, an inertial sensor is often attached to the movable body.
FIGS. 1A and 1B show a cross-section and a top view representing a conventional inertial sensor.
The schematically shown inertial sensor, as acceleration sensor 10, is fashioned in order to determine a linear acceleration, oriented in a direction 12 perpendicular to a substrate 14, of acceleration sensor 10, and to define a quantity corresponding to the acceleration. Substrate 14 forms, together with a frame part 16 and a capping wafer 18, a housing of acceleration sensor 10 enclosing an inner volume 20. Capping wafer 18 is fastened to frame part 16 via a sealing glass layer 22. Remaining areas of an insulating layer 24 and of a metallic and/or semiconductor layer 26 are situated between substrate 14 and frame part 16.
A seismic mass 28 of acceleration sensor 10 is situated in inner volume 20. FIG. 1B shows a top view of a lower side 30 of seismic mass 28. Seismic mass 28, connected to an anchor 34 via four flexible springs 32, is fashioned as an anti-symmetrical rocker that is capable of rotation relative to the housing of acceleration sensor 10 about an axis of rotation 36. Seismic mass 28 has a mass distribution that is anti-symmetrical relative to axis of rotation 36. The bending rigidity of flexible springs 32 is designed such that the linear acceleration of acceleration sensor 10 in direction 12 causes a movement of seismic mass 28 out of its initial position and relative to the housing of acceleration sensor 10 about axis of rotation 36.
In order to determine the movement of seismic mass 28 out of its initial position about axis of rotation 36, acceleration sensor 10 has detection electrodes 38a and 38b that are situated adjacent to lower side 30, in stationary fashion, opposite the housing made up of components 14 through 18. Detection electrodes 38a and 38b are electrically insulated from substrate 14 via partial areas of insulating layer 24.
If acceleration sensor 10 experiences an acceleration in direction 12, then the average distances d1 and d2 between lower side 30 and detection electrodes 38a and 38b change due to the anti-symmetrical mass distribution of seismic mass 28 relative to axis of rotation 36. The capacitances of a first capacitor, formed from detection electrode 38a and a partial surface of lower side 30, and of a second capacitor, formed from second detection electrode 38b and a further partial surface of lower side 30, change corresponding to the changes in average distances d1 and d2. In this manner, a magnitude of the acceleration in direction 12 can be determined via an evaluation of the capacitances of the capacitors. Because certain methods for evaluating the capacitances of the capacitors of acceleration sensor 10 are conventional, they are not described in more detail here.
In order to provide a reliable determination of a position of seismic mass 28 relative to the housing of acceleration sensor 10, it is advantageous to keep average distances d1 and d2 as small as possible. However, this creates the risk that when there is a significant acceleration in direction 12, areas of seismic masses 28 will strike against the housing of acceleration sensor 10. In order to prevent a large-surface contact between seismic mass 28 and the housing of acceleration sensor 10 given a collision with seismic mass 28, raised stops 40 are fashioned on lower side 30. In addition, stop electrodes 42a and 42b are fastened to substrate 14 that are electrically insulated from substrate 14 by remaining areas of insulating layer 24. The contact between seismic mass 28 and the housing of acceleration sensor 10 is thus limited to a contact between a stop 40a or 40b and a stop electrode 42a or 42b. 
However, it is possible that, due to a mechanical overload, stop 40a or 40b will strike against a stop electrode 42a or 42b so strongly that stop 40a or 40b remains suspended from stop electrode 42a or 42b. This is referred to as stiction of stop 40a or 40b on stop electrode 42a or 42b. In addition, given a strong overload, at least a partial area of stop 40a or 40b can break away from seismic mass 28, which is often referred to as particle formation upon an impact of stop 40a or 40b against stop electrode 42a or 42b. It is desirable to have available a possibility by which stiction and/or particle formation can be prevented in a sensor device of this general type.